The present invention relates to a blade member, a blade member manufacturing method, a developing unit having a blade member, and an image forming apparatus having a developing unit and, more particularly, to a member or blade member used in an image forming apparatus such as a copying machine, a laser beam printer, or the like to adjust the amount of toner.
A copying machine or laser beam printer has a blade member incorporated in its developing unit to serve as a toner amount adjusting member. When the toner of the developing unit is attached to a latent image photosensitized on a photosensitive drum to develop the image, the blade member adjusts the amount of toner of the developing unit. This will be described with reference to the accompanying drawings. FIG. 1 shows a sectional view of the main part of a developing unit manufactured by the present applicant.
Referring to FIG. 1, reference numeral 1 denotes the case of a developing unit; 2, a photosensitive drum; 4, a developing sleeve; 6, a magnet mounted in the developing sleeve 4; and 8 and 10, toner agitating screws, respectively.
Reference numeral 12 denotes a blade member according to the present invention. The blade member 12 is fixed to blade holding members 16 and 18 with a blade attaching member 14.
FIG. 2 shows a partial enlarged view of the structure of a position near the distal end of the blade member 12 and the developing sleeve 4. As shown in FIG. 2, the distal end of the blade member 12 is constituted by two metal members. A first metal member 12A is made of a nonmagnetic material. A distance between a distal end position 12A-a of the first metal member 12A and the outer surface of the developing sleeve 4 is adjusted to adjust the toner amount. A second metal member 12B is made of a magnetic material, and constitutes a magnetic circuit together with a magnet in the developing sleeve 4 to attract the toner. Accordingly, the blade member 12 having the above arrangement is constituted by the two metal members, one of which is composed of the magnetic member.